Bucking tradition is something Overlord does very well as a series. It presents a cast of characters that would usually be the villains of a show and manages to get you to pull for them in spots. They aren't all just psychotic characters who are out to murder everyone and bathe in the blood of their enemies.
Look no further than Ainz, who is a well-rounded character, showing some of the darker traits you'd expect from an Overlord and mixing in genuine care he has for his companions. It's an interesting mix of likable characters.
10 Demiurge
He wears two faces around others. To those who live in Nazarick with him, he can be a kind demon who's gentle to those in need of his care. That face disappears once he's in contact with a foe, showing off a sadistic side that's unrivaled by anyone else in the show. He gleefully tortures others, oftentimes doing it right in front of their friends. He gets a twisted glee from their pain and suffering, going so far as wanting to give his prisoners hope before swallowing them up in despair.
9 Narberal Gamma
A character with such an immense hatred for humans is going to be hard to be very likable. It isn't a dislike she even tries to hide, openly wearing it on her sleeve whenever she encounters one. This hate doesn't lead to her killing them indiscriminately, however, the feeling is always simmering beneath her. Nonetheless, she's a trusted confidant of Ainz, one of those who accompanied him as he attempted to be a hero, showing the restraint she has as she constantly fought the urge to kill anyone who was rude to her master.
8 Shalltear Bloodfallen
She's loyal to Ainz and honest to those around her, that's about the only positive traits that Shalltear has to her. That loyalty only applies to Ainz as she's killed her subordinates due to their failure before.
This lack of patience is her most negative and annoying trait as she can fly off the handle regularly over anything she deems a failure. As a vampire, seeing too much blood can also send her off the deep end, tearing her victims apart.
7 Pandora's Actor
Over the top is the best way to describe Pandora's Actor, he's the type of person who has no idea how to scale back, always taking things up to 11. It makes him a fun character to have around, especially when he's grating on others around him. He's also not afraid to ask for clarification on a task or offer up his own suggestions, showing he has more of a backbone than some. That said, the bombastic qualities of his personality can make him a tad annoying at times.
6 Albedo
While she's very clingy towards Ainz, Albedo's one of the more likable NPCs under his employ. She isn't afraid to speak her mind during discussions, willing to challenge anyone if she feels their plan isn't good. With how calm and collected she can be, her ideas often surpass even her masters, making her his chief council. Unfortunately, she's also a very jealous character, one that's prone to outbursts whenever she feels someone is getting close to Ainz. Still, it's hard not to relate to someone as in love as she is.
5 Mare Bello Fiore
Mare is a bundle of nerves, a tower of cards that are perpetually on the verge of collapsing. It makes him an interesting character as he's a wholly subservient character in a sea of dominant ones.
His fears are always on display with the stutter he has in his speech and the cowardice he has to ever being scolded by Ainz. The one drawback to his character is that he's so crippled by his nerves that he struggles to ever do anything on his own, always preferring to be with his sister.
4 Ainz
It's hard to gauge Ainz as, at times, he can be incredibly selfish, only caring about his progression, particularly when it comes to experimenting with his powers. On the other side of the coin, he's also very caring to his NPCs, wanting them to enjoy themselves and not be overly burdened by work. His loyalty can be unmatched once you've earned his respect or trust. He's also open to differing viewpoints than his own, far from the dictator you'd expect from his appearance.
3 Aura Bella Fiora
It's hard not to like the cheery dark elf who injects a needed bit of cheerfulness among the gloomy floor guardians. She's filled with so much zest that at times she feels out of place among the others, which makes her such a great character. While she is loyal to Ainz and would do just about anything for him, she also has her own goals, wanting to collect as many unique beasts as she can. She's also very protective of her brother, despite being more than a little bossy to him.
2 Cocytus
Cocytus is like a samurai from ancient times, bound entirely by a code of honor. Among the floor guardians, some of which are fully psychopathic, he offers a breath of fresh air in the same way Aura does. He's constantly evolving, growing into being more assertive and willing to stand up to Ainz, something very few are willing to do. The struggles he has with inadequacy and how he feels he can't serve Ainz, as well as others, do is so relatable.
1 Sebas Tian
Battle butler is one way you could describe Sebas as he's the leader of the Pleiades Six Stars and has a personality so different from them. He has heroic tendencies that you don't see in other characters other than Cocytus. He won't hesitate to go out of his way to help someone, even if it may end up angering Ainz. He's sympathetic to those who are struck by a plight and doesn't hate humanity as many of his kin do. He's always felt the strong should protect the weak, making him the most likable member of the Nazarick.